diff options
| author | Jason Baron <jbaron@redhat.com> | 2010-09-17 11:09:00 -0400 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2010-09-22 16:29:41 -0400 |
| commit | bf5438fca2950b03c21ad868090cc1a8fcd49536 (patch) | |
| tree | 9fc5693763263704de8d8ba1c37a84172dbe5eb7 /arch | |
| parent | fa6f2cc77081792e4edca9168420a3422299ef15 (diff) | |
| download | linux-bf5438fca2950b03c21ad868090cc1a8fcd49536.tar.bz2 | |
jump label: Base patch for jump label
base patch to implement 'jump labeling'. Based on a new 'asm goto' inline
assembly gcc mechanism, we can now branch to labels from an 'asm goto'
statment. This allows us to create a 'no-op' fastpath, which can subsequently
be patched with a jump to the slowpath code. This is useful for code which
might be rarely used, but which we'd like to be able to call, if needed.
Tracepoints are the current usecase that these are being implemented for.
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jason Baron <jbaron@redhat.com>
LKML-Reference: <ee8b3595967989fdaf84e698dc7447d315ce972a.1284733808.git.jbaron@redhat.com>
[ cleaned up some formating ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/Kconfig | 3 | ||||
| -rw-r--r-- | arch/x86/include/asm/alternative.h | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/alternative.c | 2 |
3 files changed, 6 insertions, 2 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index 4877a8c8ee16..1462d8492d89 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -158,4 +158,7 @@ config HAVE_PERF_EVENTS_NMI subsystem. Also has support for calculating CPU cycle events to determine how many clock cycles in a given period. +config HAVE_ARCH_JUMP_LABEL + bool + source "kernel/gcov/Kconfig" diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h index 634bf782dca5..76561d20ea2f 100644 --- a/arch/x86/include/asm/alternative.h +++ b/arch/x86/include/asm/alternative.h @@ -4,6 +4,7 @@ #include <linux/types.h> #include <linux/stddef.h> #include <linux/stringify.h> +#include <linux/jump_label.h> #include <asm/asm.h> /* @@ -182,7 +183,7 @@ extern void *text_poke_early(void *addr, const void *opcode, size_t len); extern void *text_poke(void *addr, const void *opcode, size_t len); extern void *text_poke_smp(void *addr, const void *opcode, size_t len); -#if defined(CONFIG_DYNAMIC_FTRACE) +#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL) #define IDEAL_NOP_SIZE_5 5 extern unsigned char ideal_nop5[IDEAL_NOP_SIZE_5]; extern void arch_init_ideal_nop5(void); diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 083bd010d92c..cb0e6d385f6d 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -641,7 +641,7 @@ void *__kprobes text_poke_smp(void *addr, const void *opcode, size_t len) return addr; } -#if defined(CONFIG_DYNAMIC_FTRACE) +#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL) unsigned char ideal_nop5[IDEAL_NOP_SIZE_5]; |